Effects of Preparation Methods of Pd Supported on (001) Crystal Facets Exposed TiO2 Nanosheets for Toluene Catalytic Combustion

Abstract

A series of TiO2 nanosheets-supported Pd catalysts were individually prepared by impregnation, deposition–precipitation, photo-deposition and in situ reduction by NaBH4. For comparison, Pd supported on P25 was prepared by the impregnation method. The experimental results show that the catalytic efficiency of the catalyst prepared with titanium dioxide nano sheet as the support is higher than that of the catalyst supported with P25. Its excellent properties are as follows: The resulting sample indicates that TiO2 nanosheets-supported Pd catalyst display an improved activity than Pd/P25, whose temperature of 100% complete conversion of toluene decreased by 40 ℃ at the most. The Pd particles on the catalyst synthesized by the light deposition method and the NaBH4 reduction method are more obvious, while the Pd particles on the catalyst synthesized by the immersion method and the deposition–precipitation method are less obvious, which shows that the latter two methods are more conducive to the dispersion of Pd. The good catalytic activity may be due to the better exposed mirror and dispersion of titanium dioxide nanosheets. This is mainly related to the exposed crystal plane of the nanosheet TiO2 (001), which made it easier to form the oxygen vacancy. Moreover, among all of the TiO2 nanosheets-supported Pd catalysts, Pd/TiO2 NS (TiO2 NS means TiO2 nanosheets) prepared by the impregnation method show the highest catalytic activity. The XRD results show that Pd prepared by impregnation is more dispersed and smaller. This is due to PdO being dispersed more efficiently than the others, leading to more Pd active sites.